Mesothelioma: Types, causes & symptoms

Mesothelioma is a type of cancer that begins to grow in the inner lining of the chest or the outer lining of the lungs (pleura), heart, or stomach. The cancer cells multiply and they begin to form small lumps, called tumours. The tumours then spread and make it difficult for you to breathe.

This information focuses on mesothelioma of the lungs, sometimes called malignant pleural mesothelioma.

There are three different types of pleural mesothelioma:

• Epithelioid mesothelioma is the most common type. This type of mesothelioma spreads more slowly than the others.  
• Sarcomatoid mesothelioma is less common. It usually progresses more quickly and has a poorer outcome from treatment. 
• Biphasic mesothelioma is uncommon. Biphasic tumours have some parts which are epithelioid and some parts which are sarcomatoid.

The main cause of mesothelioma is breathing in asbestos dust.  Asbestos is a material used in construction and other industries that was banned in the UK in 1999.

Asbestos fibres are extremely small. When you breathe them in, they get inside your lungs and cause irritation. Over time, they can cause changes to your genes, which eventually causes mesothelioma to develop.

People who worked in industries that used asbestos are at higher risk of developing mesothelioma. This includes: 

• construction workers 
• plumbers
• electricians
• carpenters
• laggers and insulation workers
• dockers and shipbuilders
• train engineers
• metal workers
• painters
• naval sailors

The Health and Safety Executive have more information on who is at risk of asbestos exposure.

There is also a small risk of getting mesothelioma if you lived with someone who worked with asbestos. They may have carried asbestos fibres home on their clothing, where other people could breathe them in.  

Because it takes a long time to develop, mesothelioma is most common in older people. The average age at diagnosis is 75. It is more common in men, who make up about 8 in 10 cases. 

The symptoms of mesothelioma usually develop over time.  In the early stages there often are not many symptoms, but as the cancer grows symptoms start to develop. 

The main symptoms are: 

• cough
• tiredness (fatigue)
• shortness of breath
• chest pain
• losing weight 
• loss of appetite
• sweating
• difficulty swallowing
• a hoarse voice.

Some people have changes in the shape of their fingers, such as becoming more curved or larger at the ends. This is called finger clubbing.  

As mesothelioma develops, it often causes fluid to build up in your lungs. This is called a pleural effusion. This build-up of fluid stops your lungs from expanding fully as you breathe. This can make you feel out of breath.